Screw operated scissors jack



Dec. 6, 1966 G. L. WHITE 3,290,008

SCREW OPERATED SGISSORS JACK Filed May 24, 1965 2 Sheets-Sheet 1 I NVEN TOR.

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Dec. 6, 1966 G. WHITE 3,290,008

SCREW OPERATED SCISSORS JACK Filed May 24, 1965 2 Sheets-Sheet z 4:, ywdtw A fro/11a y.

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United States Patent 3,290,008 SCREW OPERATED SCISSORS JACK Gaylord L. White, 717 2nd St., Beiton, Mo. Filed May 24, 1965, Ser. No. 457,982 Claims. (Cl. 254-122) This invention relates to new and useful improvements in jacks, and has particular reference to a jack especially designed for use in connection with automotive vehicles, although it will be readily apparent that its use is not so limited.

The principal object of the present invention is the provision of a jack of the type comprising a generally horizontal scissors-type linkage consisting of a pair of levers pivoted together intermediate their ends on a horizontal axis, lifting of the vehicle or other load being accomplished by vertical separation of one corresponding set of ends of said levers, and having manually operable means including an elongated screw for separating the opposite corresponding set of ends of said levers. Said screw is alternatively positioned vertically, whereby it normally extends Well above the load platform of the jack, and provides the best mechanical advantage in the lower portion of its lift, or is positioned horizontally, whereby it is disposed below the level of the work platform and provides the best mechanical advantage in the upper portions of its lift. The first position is used when the load platform is to be diposed between the vehicle wheels and the ground, as is commonly done when is is desired to level house trailers, vehicles having camper bodies, and the like. In this usage the lift is generally low, so that the best mechanical advantage is required in the initial stages of operation of the jack. Also, with with the jack platform beneath the wheel, the jack screw may be positioned outwardly from the side of the vehicle so that extension of said screw above the jack platform is permissable. The horizontal position of the screw, however, is used when the vehicle is to be elevated by placing the jack platform under a portion of the vehicle frame, as for example when desiring to change a tire or wheel. In this usage, the lift must start with the jack already partially extended, since the vehicle frame is of course disposed well above the ground, and therefore it is preferable that the jack provide its best mechanical advantage in the upper portions of its range. Also, since the vehicle frame is usually disposed well inwardly from the edges of the vehicle body, any substantial extension of tie screw above the load platform cannot be permitted since it would interfere with the bottom surfaces of the vehicle body.

Other objects are simplicity and economy of construction, efiiciency and dependability of operation, and adaptability for use in a wide variety of applications.

With these objects in view, as well as other objects which will appear in the course of the specification, reference will be had to the accompanying drawing, wherein:

FIG. 1 is a vertical sectional view of a jack embodying the present invention, taken on line I-I of FIG. 6, with parts left in elevation and parts broken away, and showing the parts thereof assembled for use with the jack screw disposed vertically,

FIG. 2 is a view similar to FIG. 1, but showing the jack parts assembled for use with the jack screw disposed substantially horizontally,

FIG. 3 is a sectional view taken on line LIL-III of FIG. 1, with parts broken away,

FIG. 4 is a sectional view taken on line IVlV of FIG. 1, with parts broken away,

FIG. 5 is a slightly irreglar sectional view taken on I line VV of FIG. 2, with parts broken away, and

assists Patented Dec. 6, 1965 FIG. 6 is a sectional view taken on line VIVI of FIG. 1.

Like reference numerals apply to similar parts throughout the several views, and the numeral 2 applies to a ground-engaging base plate which may be rectangular as shown or of any. other desired shape, and formed preferably of sheet steel, and a load platform 4 also formed of sheet steel and disposed above base plate 2. Said platform has a horizontal central portion 6 adapted to support a load, and a downwardly angled ramp portion 8' at each end thereof, the lower edges of said ramp portions being adapted, when the jack is completely lowered, to rest on and be supported by base plate 2. If the jack is to be disposed directly beneath a wheel of the vehicle, the wheel may be moved onto central portion 6 of the platform by driving the vehicle under its own power, ramps 8 facilitating this operation. It will be noted that the platform is disposed above one side of the base plate, so that when the jack is disposed relative to a vehicle as just described, the opposite side of the base plate may extend outwardly from the side of the vehicle.

Base plate 2 and platform 4 are connected by a scissors-type linkage consisting of a pair of levers 10 and 12. Lever 10 consists of a pair of parallel, spaced apart bars 14, and lever 12 consists of a pair of parallel, spaced apart bars 16, all of said bars being pivotally connected together intermediate their ends by a horizontal pivot pin 18 which is parallel to the longitudinal axis of load platform 4. Matching ends of bars 14 are connected by pivot pin 20 to a block 22 welded centrally to the lower surface of platform 4. The opposite ends of bars 14 are connected by pivot pin 24 to the upstanding legs 26 of a U-shaped slide member 28, the connecting portion 30 of which is supported slidably on the upper surface of base plate 2. Pivots 18, 20 and 24 are parallel, and slide 28 is held downwardly against the base plate, but permitted to slide thereon in a direction at right angles to said pivots, by an elongated guide bar 32 overlying the connecting portion 30 of the slide and affixed at its ends to the base plate. Pivot pin 24 extends outwardly in both directions from the distal sides of lever bars 14, and has an enlarged planar washer 34 secured concentrically to each extended end thereof by a screw 36.

Matching ends of bars 16 of lever 12 are connected respectively by pivot pins 38 to a pair of blocks 40 welded to the upper surface of base plate 2, pins 38 lying directly beneath and in the same vertical plane as pivot 20. To the opposite end of each lever bar 16 is pivoted one end of a link 42, these pivots being indicated at 44, and being coaxial to each other and parallel to pivots 18 and 38. A rectilinear block 46 extends between the free ends of links 42, and is pivotally connected thereto, as at 48, on an axis parallel to its longitudinal axis, and parallel to pivots 44. Said block is provided at its mid-point with a bore 50 extending laterally therethrough, and with a stub shaft 52 affixed thereto and extending therefrom at right angles to the axis of bore 50. Pivoted respectively to the opposite ends of block 46, coaxially with the pivots d3 of links 42, are a second pair of links 54, links 54 being generally of the same length as links 42, and each having an axially opening notch 56 formed at the opposite free end thereof for enagaging pivot pin 24 in one type of operation, as will be described.

A stout, elongated jack screw 58 extends sL dably through bore 50 of block 46. Affixed to one end of said screw is a pressure block 60 having a slot 62 formed across the outer surface thereof so as to be disposed diametrically of the screw. In one type of operation, this slot engages a pin 64 extending between and fixed in bars 14 of lever 10, said pin being parallel to and disposed in adjacent but spaced apart relation to pivot pin 24. Affixed to the opposite end of screw 58 is a block 66 having a slot 68 formed therethrough. The base portion of said slot extends diametrically of the screw so as to engage over pivot pin 18 in another type of operation. Said slot open-s through a lateral face of said block, and is inclined toward the opposite end of the screw as best shown in FIGS. 1 and 2.

Threaded on screw 58 intermediate blocks 46 and 64) is a nut 70 which is adapted to operate against the adjacent face of block 46, a ball thrust bearing 72 being interposed therebetween to reduce friction. Externally, nut 70 is toothed to form a bevel gear 74 which is meshed with a second bevel gear 76 which is mounted rotatably on stub shaft 52. The bevelled teeth of gear 76 are also extended parallel to shaft 52 to form a cylindrical ratchet pinion wheel 78. Mounted rotatably on shaft 52, outwardly from gear 76, is the hub portion 80 of a radially extending handle 82, which may be of any desired length, although it is broken away to conserve space in the drawing. Adjacent gear 76, a ratchet dog 84 is pivoted intermediate its ends to handle 82 by a bolt 86 parallel to shaft 52 and spaced outwardly from pinion 78. As best shown in FIG. 3, said dog is provided respectively at its opposite ends with teeth 88 and 90 adapted to be brought respectively into engagement with the teeth of pinion 78 by tilting said dog on bolt 86. As shown, tooth 88 engages the pinion, and is urged resiliently thereagainst by a compres-sion spring 92 engaging at its one end a pin 94 affixed to the midpoint of dog 84 in spaced relation above bolt 86, and engaging at its opposite end a pin 6 carried by a block 98 affixed to handle 82 in spaced relation above the dog. Thus as handle 82 is moved in a clockwise direction, as viewed in FIG. 3, dog tooth 88 ratchets freely over the teeth of pinion 78, but when handle 82 is moved in a counter-clockwise direction, dog tooth 88 locks into pinion 78 and causes said pinion to turn with said handle to rotate gear 74 and nut 70 to advance said nut along screw 58. If dog 84 is pivoted manually in a clockwise direction, again as viewed in FIG. 3, past a dead-center position in which teeth 88 and 90 are spaced equally from the pinion, spring 92 then urges tooth 90 against the pinion, whereby oscillation of handle 82 will then cause opposite rotation of gears 76 and 74 to advance nut 70 in the opposite direction on screw 58.

In operation, if load platform 6 is to be placed directly beneath a vehicle wheel, or if the jack is to be used in any other application requiring that the lift commence at a very low elevation above base plate 2, levers 10 and 12 are first lowered to a horizontal, coextensive position, with both ends of screw 58 disconnected. The ramps 8 of the load platform then rest directly on the base plate, so that the vehicle wheel may easily be driven onto the platform. It will be seen that the distance between pivot 18 and pivot 44 is somewhat less than the distance between pivots 18 and 24, in order that the bars 16 of lever 12 will not interfere with the extended ends of pivot pin 24 as the levers are lowered to horizontal positions. Then, after first threading screw 58 manually through nut 70 to obtain the proper extension of the screw below block 46, slot 62 of block 60 of the screw is engaged over pin 64 of lever 16, as shown in FIG. 1. Links 42, position block 46 sufiiciently far above the levers that there is ample space therebetween to accommodate nut 70 and gear 74. The operator then oscillates handle 82 as previously described to advance nut 78 upwardly along screw 58, thereby elevating block 46, which acts through links 42 to elevate pivots 44 and thus to cause levers 18 and 12 to pivot relatively on pivot 18 to elevate platform 6. Slide 28 of course slides along the base plate toward pivot 38 during this operation, but is held down by guide bar 32, whereby to stabilize the linkage against tilting on pivot 38. By reversing ratchet dog 84, also as previously described, the load may of course be lowered. In

this type of operation, characterized by the position of the parts shown in FIG. 1, screw 58 is of course compressively loaded, and links 54 are not used, simply being pivoted out of the way as shown.

When the jack is to be placed beneath the frame of a vehicle, as in changing a wheel, or in any other application in which the lift is to start at a substantial elevation above the base plate, the parts are arranged as shown in FIG. 2. In this usage, load platform 6 is first manually lifted to the approximate elevation desired, and then links 42 are pivoted to be inclined outwardly and downwardly from pivots 44, and the notches 56 at the outer ends of links 54 are engaged over the extended end portions of pivot pin 24, being secured thereon by washers 34. Slot 68 of block 66 of screw 58 is then engaged on pivot pin 18, block 66 and its slot 68 acting as a hook for supporting a tensile load in screw 58. Then, by oscillating handle 82 as before, nut 70 may be advanced along the screw toward pivot 18, causing block 46 to tend to straighten the toggle linkage formed by links 42 and 54, and elevating load platform 6. Links 42 of course form one leg of the toggle, and links 54 the other leg. Said links are under compression, and screw 58 is under tension, during this type of operation.

The advantages of being able to use alternatively either the arrangement of parts shown in FIG. 1 or the arrangement shown in FIG. 2 are substantial, particularly in connection with automotive vehicles. When load platform 6 is to be placed directly beneath a vehicle wheel, as for levelling the living quarters of a trailer, or of a truck having a camper body, or for other similar purposes, the lifts required will be generally small, but must start fro-m a minimum elevation. In this case the FIG. I arrangement is use-d, since it provides a better mechanical advantage, and hence easier lifting, in the lower ranges of elevation than the FIG. 2 arrangement, since in FIG. 1 the screw 58 applies force to levers 10 and 12 with a longer moment arm, as measured by the horizontal distance between the axis of the screw and the vertical plane of pivot 18, than is possible in FIG. 2, wherein during the lower ranges of lifting the toggle legs 42-54 are acutely angled to each other and therefore can apply only a relatively small vertical force tending to elevate pivots 44. Moreover, in this usage screw 58 can be disposed in outwardly spaced relation from the vehicle, so that vertical extension of said screw above platform will not cause said screw to interfere with the vehicle body.

On the other hand, when the platform 6 enters the upper reaches of its lift, the advantage of better mechanical advantage for the FIG. 1 arrangement disappears, and the FIG. 2 arrangement has the better advantage, since in the FIG. 1 arrangement the distance between screw 58 and the vertical plane of pivot pin 18 decreases, and in the FIG. 2 arrangement toggle 4254 becomes more nearly straight, so that a greater elevating force will be applied to pivots 44 even with less tensile load on the screw. Therefore, if platform 6 is to start its lift at a relatively high elevation, as when it is placed beneath the frame or chassis of a vehicle for elevating the same to change a wheel or the like, the FIG. 2 arrangement is used. Also, when platform 6 is disposed as just described, it is quite likely that screw 58 will be disposed beneath the vehicle body, and would interfere with said body, if dispose-d vertically as in FIG. 1. The substantially horizontal. disposition of the screw as shown in FIG. 2 prevents any such interference, in that said screw is always entirely beneath the level of platform 6. Also, in FIG. 2 it will be seen that handle 82 extends substantially horizontally so that it may extend outwardly from the side of a vehicle so as to be easily grasped and manipulated, and that it oscillates in a horizontal plane so that its pivotal movement will not be interfered with either by the ground beneath or by the vehicle body above.

While I have shown and described a specific embodiment of my invention, it will be readily apparent that many minor changes of structure and operation could be made without departing from the spirit of the invention as defined by the scope of the appended claims.

What I claim as new and desire to protect by Letters Patent is:

1. A jack comprising:

(a) a base plate,

(b) a load platform disposed above said base plate,

(c) a pair of levers pivotally joined together intermediate their ends by a horizontal pivot pin and extending horizontally in both directions from said pin, a first pair of corresponding ends of said levers being pivotally connected respectively to said base plate and said platform on axes parallel to said pivot (d) a slide member carried by said base plate for horizontal movement at right angles to said pivots,

(e) a second pivot pin parallel to said first pivot pin and connecting the opposite end of the lever connected to said platform to said slide member,

(f) a link pivoted at one end to the opposite end of the lever connected to said base plate on an axis parallel to said first pivot pin,

(g) a block pivoted to the opposite end of said link on an axis parallel to said first pivot pin,

(h) a second link pivoted at one end to said block coaxially with said first link and being detachably engageable at its opposite end with said second pivot pin,

(i) a screw slidably engaged in said block and extending at right angles to the pivotal axis of said block, said screw being selectively engageable at an end thereof either with said first pivot pin or with the lever connected to said slide member at a point adjacent said slide member, and

(j) operating means for advancing said screw longitudinally in either direction with respect to said block.

2. The structure as recited in claim 1 wherein said operating means comprises:

(a) a nut threaded on said screw adjacent said block,-

and

(b) means carried by said block and manually operable to rotate said nut selectively in either direction, said screw being secured against rotation about its longitudinal axis by its engagement either with said first pivot pin or with said lever.

3. The structure as recited in claim 1 wherein said operating means comprises:

(a) a nut threaded on said screw adjacent said block, and being externally toothed to form a first bevel gear,

(b) a stub shaft afiixed to said block and extending therefrom at right angles to said screw,

(c) a second bevel gear rotatably mounted on said stub shaft and meshing with said first bevel gear, said second bevel gear also including a toothed ratchet pinion,

(d) a handle pivoted on said stub shaft adjacent said pinion, and

(e) a ratchet dog carried by said handle and engaging said pinion, whereby oscillation of said handle will cause rotation of said pinion in one direction only.

4. The structure as recited in claim 3 wherein said ratchet dog is reversible whereby to cause rotation of said pinion selectively in either direction.

5. The structure as recited in claim 2 wherein said lever pivoted to said slide member is provided adjacent said slide member with a support pin afiixed thereto parallel to said first pivot pin, wherein said screw is provided at one end with pressure member transversely slotted across its outer end to engage pivotally and non-rotative- -ly over said support pin to support a compressive load in said screw, wherein the opposite end of said screw has affixed thereto a hook member for engaging pivotally but non-rotatably over said first pivot pin to support a tensile load in said screw, and wherein said nut is threaded on said screw intermediate said block and said pressure member.

References Cited by the Examiner UNITED STATES PATENTS 2,704,199 3/1955 Olson 2S4122 FOREIGN PATENTS 608,937 5/ 1926 France. 657,637 1/ 1955 France.

WILLIAM FELDMAN, Primary Examiner, O. M. SIMPSON, Assistant Eqqamirger 

1. A JACK COMPRISING: (A) A BASE PLATE, (B) A LOAD PLATFORM DISPOSED ABOVE SAID BASE PLATE, (C) A PAIR OF LEVERS PIVOTALLY JOINED TOGETHER INTERMEDIATE THEIR ENDS BY A HORIZONTAL PIVOT PIN AND EXTENDING HORIZONTALLY IN BOTH DIRECTIONS FROM SAID PIN, A FIRST PAIR OF CORRESPONDING ENDS OF SAID LEVERS BEING PIVOTALLY CONNECTED RESPECTIVELY TO SAID BASE PLATE AND SAID PLATFORM ON AXES PARALLEL TO SAID PIVOT PIN, (D) A SLIDE MEMBER CARRIED BY SAID BASE PLATE FOR HORIZONTAL MOVEMENT AT RIGHT ANGLES TO SAID PIVOTS, (E) A SECOND PIVOT PIN PARALLEL TO SAID FIRST PIVOT PIN AND CONNECTING THE OPPOSITE END OF THE LEVER CONNECTED TO SAID PLATFORM TO SAID SLIDE MEMBER, (F) A LINK PIVOTED AT ONE END TO THE OPPOSITE END OF THE LEVER CONNECTED TO SAID BASE PLATE ON AN AXIS PARALLEL TO SAID FIRST PIVOT PIN, (G) A BLOCK PIVOTED TO THE OPPOSITE END OF SAID LINK ON AN AXIS PARALLEL TO SAID FIRST PIVOT PIN, (H) A SECOND LINK PIVOTED AT ONE END TO SAID BLOCK COAXIALLY WITH SAID FIRST LINK AND BEING DETACHABLY ENGAGEABLE AT ITS OPPOSITE END WITH SAID SECOND PIVOT PIN, (I) A SCREW SLIDABLY ENGAGED IN SAID BLOCK AND EXTENDING AT RIGHT ANGLES TO THE PIVOTAL AXIS OF SAID BLOCK, SAID SCREW BEING SELECTIVELY ENGAGEABLE AT AN END THEREOF EITHER WITH SAID FIRST PIVOT PIN OR WITH THE LEVER CONNECTED TO SAID SLIDE MEMBER AT A POINT ADJACENT SAID SLIDE MEMBER, AND (J) OPERATING MEANS FOR ADVANCING SAID SCREW LONGITUDINALLY IN EITHER DIRECTION WITH RESPECT TO SAID BLOCK. 